and Susan E. Aiello, DVM, ELS
Patellar luxation is hereditary and especially common in small and toy breeds of dogs.
Affected animals may also have other leg or joint problems. The patella (or kneecap) lies in a "track" on the front of the leg, where it functions in joint movement, sliding up and down easily as the knee bends and extends. In some dogs and less commonly in cats, the patella does not stay in its track, occasionally slipping (or luxating), usually to the inside of the leg. When this happens, it is called patellar luxation.
Signs of patellar luxation in dogs vary depending on how severe the problem is.
Most dogs tend to skip or hop when walking or especially when running, but some dogs and cats may hold the leg up completely.
Damage caused by the kneecap slipping in and out of its track can eventually lead to arthritis in the knee.
Your veterinarian can generally diagnosis this problem by palpating the knee joint, but x-rays are often recommended to look for arthritis or other problems.
Many dogs with patellar luxation do fine without any treatment or with only occasional pain relievers or anti-inflammatory medication.
Surgery may be needed in more severe cases or in overweight dogs that typically have much more of a problem when the patella slips. Getting your dog's weight under control is important in management of this condition in overweight dogs.